Let's compare Muhammad, and the writings in the Quran, to the signs of a compulsive liar. I got these quotes from https://blog.udemy.com/compulsive-lying-disorder/ but you can look at any other list of the symptoms of pathological lying disorder and Muhammad will match most of them.

Frequent Unnecessary Dishonesty

The symptom most easily recognized when diagnosing Compulsive Lying Disorder is frequent unnecessary dishonesty. Individuals will lie about anything and everything, even in cases when they have nothing to gain from concealing the truth. For example, an individual affected with this unfortunate disorder may lie when asked what his or her favorite food or drink is. In the majority of situations in which this question is asked there is no logical reason for answering dishonestly, yet a compulsive liar will automatically. This often results in inconsistency in relationships when the compulsive liar happens to be incapable of keeping track of his or her lies.

Muhammad would make up bizarre stories when asked pretty much any question at all.

Attention Seeking Behavior

Compulsive lying disorder often develops very early in childhood due to a child’s need or desire to seek out attention from caregivers and peers. By fabricating stories in childhood, they often gained the fascination and disbelief of those around them, which led to others paying more attention to the extraordinary nature of the child’s story. Children have vivid imaginations, so at first parents often brush off the child’s lies and allow them to get away with it under the assumption that the child will simply “grow out of it”. However, if the lying behavior is allowed to go on too long, then it becomes nearly irreparable and compulsive lying disorder develops.

Fits Muhammad perfectly. Abandoned child seeking attention.

Story Fabrication

Compulsive liars feel the constant need to convey to others that they are superior and deserving of more attention then the other children in their cohort. In order to achieve this goal, they construct elaborate stories about themselves, often involving fantastic adventures and incredible feats that are intended to display them as a hero in the eyes of their peers. However, once the individual is caught in the lie, they are looked upon with contempt and dislike, which then causes them to lie even more in order to shake the unpleasant label. Once the compulsive liar reaches adulthood, these mystical stories because more grounded in nature, but still maintain their awe-inspiring intent.

Obviously this is the key symptom which convicts Muhammad. The Quran is the physical evidence of the above symptom.

Covering Up

Though compulsive liars often take extreme care to keep others under the spell of their deception, once in awhile the web of lies unravels and the liar is seen as is without any of his dishonest walls. When this occurs, the liar works quickly and frantically to rebuild those walls, constructing more lies in order to rebuild himself into what he was previously seen as. This often involves elaborate stories of being falsely accused, constructing lie after lie with the intention of defending his or her supposed innocence. If this method, as well as any other attempt at lying, fails and the compulsive liar is forced to tell the truth, he or she will often become incredibly nervous and display a great deal of uncomfortable behavior.

A new Surah always seemed to be required to fix the previous ones that turned out not to be so perfect after all.

Same Story, Different Characters

Plagiarism is a key factor in the life of a compulsive liar. This often involves twisting and warping stories heard from peers, acquaintances, or movie plotlines into plausible adventures that could have occurred in the liar’s life. Crafting these storylines takes a great deal of effort on the part of the individual since the biggest fear of a compulsive liar is being “found out”. Of course, much of this effort is done subconsciously, which results in individuals being unable to recall that the story is a lie. If a compulsive liar was attached to a lie detector machine, it’s likely that their statements would come across as the truth simply because they’ve told them so many times that they sincerely believe the fabricated event actually occurred.

Again, the Quran is the physical evidence. It shows exactly what the quote described.

Low Self-Esteem

Many cases of compulsive lying disorder development can be attributed to low feelings of self worth and an inferiority complex. These factors typically influence individuals to seek out alternative methods, including lying or crafting stories, to feel better about themselves. However, when the dishonesty and false endeavors fail to impress those around the compulsive liar, their self esteem sinks even lower, which causes more extreme fabrications to come to the surface.

Yup, Muhammad alright.

Personality Disorders and Addiction

The two main personality disorders that contribute to the development of compulsive lying disorder are bipolar disorder and attention deficit hyperactivity disorder, more commonly known as ADHD. Bipolar disorder causes affected individuals to experience intense long lasting emotional highs and lows, sinking them into the depths of depression for months at a time before switching to the manic phase, which functions much like ADHD. Once the individual has entered the manic phase, they are more likely to exhibit dishonest behavior and speech, which leads to eventual compulsive lying disorder. Individuals affected with ADHD experience much of the same since the disorder influences them to exhibit impulsive behavior. Addiction to drugs, alcohol, gambling, or other similar factors often causes individuals to lie about their whereabouts or actions, which can potentially lead to the development of compulsive lying disorder.

While not an addict, he was almost certainly bipolar. The manic phases were when he made up the Surahs. That explains why they only came at certain times and not others, even if Muhammad wanted them to. He had to wait for a manic phase to take hold. I find Muhammad guilty of being a pathological liar. Does anyone have an objection?

Ali Sina wrote an excellent book named: "Understanding Muhammad: A Psychobiology of Allah's prophet" (May 1, 2008). Where he has Muhammad psychology analyzed by experts in Clinical Psychology. His conclusion. Muhammad suffered from acute case of Schizophrenic Paranoia, and epilepsy.

I don't believe he was schizophrenic though. His symptoms more closely match compulsive lying which stemmed from bipolar disorder. Schizos don't make up wild stories like Muhammad did, and plagiarize others with himself in the role of the original person. Take for instance the way that he made himself out to be exactly like the "prophet" Mani. If you read about Manichaeism you'll see that he did the thing about saying that prior religions were "corrupted" by their adherents so he had to come along and straighten things out. He also combined elements of several existing religions, depending one which people he was trying to convert, into his new one, exactly as Muhammad incorporated pagan Arab elements into Islam to attract the pagans. He also claimed to be the predicted "paraclete" of the NT. The parallels are so numerous and glaring that it's amazing that nobody identified Muhammad as a Mani wannabe immediately.